陇东半干旱区一次特大暴雨事件的降水极端性分析

Analysis on precipitation extremity of a torrential rain event in semi-arid region of eastern Gansu

2022年7月15日地处半干旱区的甘肃陇东出现一次特大暴雨过程,多站日雨量和小时雨量均突破历史极值。利用2022年7月14日20:00至15日20:00(北京时)逐分钟、逐小时降水观测数据,甘肃省庆阳市192个区域气象站建站以来日降水量、小时降水量资料,以及地面-卫星-雷达三源融合降水分析产品(CMA Multi-source Merged Precipitation Analysis System,CMPAS)10 min和1 h降水量数据,分析此次特大暴雨过程的降水特征及极端性。结果表明:这次特大暴雨过程具有累积降水量大、暴雨及以上量级降水落区集中、对流性降水强、降水中心稳定少动、短时强降水持续时间长等特征,其中累积降水量、降水强度和短时强降水持续时间的极端性明显。特大暴雨中心位于庆城县中北部的翟家河站,最大累积雨量达373.2 mm,是该站建站以来观测最大值,接近甘肃省所有国家站日降水量极值的2倍;最大小时雨量达84.9 mm,位居庆阳市所有测站建站以来小时雨量第3位;短时强降水最长持续时间达6 h,是庆阳市所有测站建站以来最大值。分钟级降水量演变表明,强降水中心的降水强度具有脉动变化特征,降水位置在东、西、南、北方向存在摆动,但摆动幅度较小。

An extremely heavy rainstorm occurred on 14-15 July 2022 in Longdong,Gansu Province,which is located in semi-arid re⁃gion,the daily rainfall and hourly rainfall intensity at several stations broke the historical extreme values.Based on the minutely and hourly precipitation observation data from 20:00 BST 14 to 20:00 BST 15 July 2022,the daily and hourly precipitation data from 192 re⁃gional meteorological stations since the establishment of them in Qingyang of Gansu Province,and the CMPAS(CMA Multi-source Merged Precipitation Analysis System)10-minute and hourly precipitation data,the precipitation characteristics and extremity of the torrential rain event are analyzed.The results show that the extremely torrential rain event is characterized by large cumulative precipi⁃tation,concentrated rainfall area of rainstorm and above,strong convective precipitation,stable and less movement of the rainfall cen⁃ters,and long duration of short-term strong precipitation,among which the extremities of cumulative precipitation,hourly precipitation intensity and short-term heavy precipitation duration are obvious.The heavy rainstorm center,Zhaijiahe station,is located in the middle and north part of Qingcheng County,the maximum accumulated rainfall is 373.2 mm,which is the maximum since the station establishment,and is nearly twice of daily precipitation extreme values at all national stations in Gansu Province.The maximum hourly rainfall is 84.9 mm,ranking the third in historical records at all stations in Qingyang,and the longest duration of short-term strong rain⁃fall is as long as 6 hours,which is the maximum in historical records at all stations in Qingyang since establishment of them.The evolu⁃tion of minutely precipitation shows that the precipitation intensity in the heavy precipitation center has pulsating change,and the pre⁃cipitation location has swing in the east,west,south and north,but the swing amplitude is small.